REDWOOD CITY, Calif., March 16, 2015 /PRNewswire/ -- AcelRx Pharmaceuticals, Inc. (Nasdaq: ACRX), (AcelRx), a specialty pharmaceutical company focused on the development and commercialization of innovative therapies for the treatment of acute pain, today reported dosing of the first patient in the pivotal Phase 3 study of ARX-04. ARX-04 is a non-invasive, single-use 30 mcg sufentanil sublingual tablet in a disposable, pre-filled, single-dose applicator (SDA).

This study, SAP301, is a multi-center, double-blind, placebo-controlled study that will evaluate the efficacy and safety of ARX-04 vs. placebo for the treatment of moderate-to-severe acute pain following ambulatory abdominal surgery. SAP301 is expected to include approximately 160 adult patients, randomized 2:1 active to placebo, to be treated for up to 48 hours. ARX-04 or placebo will be administered by site staff as requested by the patient, but no more than once per hour. The primary endpoint of the study is to demonstrate a statistically significant difference in the time-weighted summed pain intensity difference (SPID) of ARX-04 compared to placebo over a 12-hour dosing period (SPID-12). The study will be conducted at four sites in the United States.

"We are pleased to have our pivotal ARX-04 Phase 3 clinical trial underway. The ARX-04 product represents a promising new application of our sublingual tablet technology for delivery of sufentanil and has the potential to safely provide non-invasive, fast-acting analgesia for patients in acute pain," stated Dr. Pamela Palmer, AcelRx's founder and Chief Medical Officer. "We anticipate enrollment to take up to nine months. Pending the completion of enrollment in this study, we anticipate top-line results in the fourth quarter of 2015."

About ARX-04 The ARX-04 SDA is a non-invasive, single-use, disposable, handheld applicator that allows healthcare professionals to effectively administer tablets to a patient's sublingual space to manage their moderate-to-severe acute pain. ARX-04 consists of a 30 mcg sufentanil sublingual tablet, in a pre-filled SDA. AcelRx's proprietary tablet formulation enables sublingual sufentanil absorption when ARX-04 is placed under the tongue. As a result, ARX-04 can provide analgesia in a non-invasive method of administration and display a consistent pharmacokinetic profile due to a high percentage of drug being absorbed sublingually instead of through the gastrointestinal tract. We believe ARX-04 may be a candidate for use in a variety of medically supervised settings to manage moderate-to-severe pain, including in the emergency room, or for post-operative patients, following either short-stay or ambulatory surgery, who do not require more long-term patient-controlled analgesia, as well as for battlefield casualty treatment, and by paramedics during patient transport. According to the National Emergency Department Sample, there were more than 104 million adult emergency room visits in the U.S. during 2011, of which it is estimated that more than 48 million were associated with moderate-to-severe acute pain; while in the EU-5 there were more than 91 million adult emergency room visits during 2011, of which it is estimated that more than 34 million were associated with moderate-to-severe acute pain.

About Acute Pain In situations of trauma or injury, it is advantageous to have a rapid-acting, non-invasive method of treating acute pain. In the emergency room and in ambulatory care environments, or on the battlefield, patients often do not have immediate intravenous, or IV, access available, or maintaining IV access can be an impediment to rapid discharge. Oral pills and liquids generally have slow and erratic onset of analgesia. IV dosing results in high peak plasma levels, thereby limiting the opioid dose and requiring frequent redosing intervals to titrate to satisfactory analgesia. Additional treatment options are needed that can safely and rapidly treat acute trauma pain, in both civilian and military settings.

About AcelRx Pharmaceuticals, Inc.

AcelRx Pharmaceuticals, Inc. is a specialty pharmaceutical company focused on the development and commercialization of innovative therapies for the treatment of acute pain. AcelRx's lead product candidate, ZalvisoTM, is designed to improve the management of moderate-to-severe acute pain in adult patients in the hospital setting by utilizing a high therapeutic index opioid, through a non-invasive delivery route via a pre-programmed, patient-controlled analgesia device. AcelRx has announced positive results from each of the three completed Phase 3 clinical trials for Zalviso, and has submitted an NDA to the FDA seeking approval for Zalviso in the treatment of moderate-to-severe acute pain in adult patients in the hospital setting and on July 25, 2014, received a Complete Response Letter from the FDA. In March 2015, the Company received correspondence from the FDA stating that in addition to the bench testing and two Human Factors studies it had performed in response to the issues identified in the CRL, an additional clinical study is needed to assess the risk of inadvertent dispensing and overall risk of dispensing failures. The Company plans to meet with the FDA to discuss and clarify the need for an additional clinical study, and the potential design and objectives of such a study. The Company has two additional pain treatment product candidates, ARX-02 and ARX-03, which have completed Phase 2 clinical development. For additional information about AcelRx's clinical programs, please visit www.acelrx.com.

Forward-Looking Statements

This press release contains forward-looking statements, including, but not limited to, statements related to the completion of enrollment in SAP-301, the Company's first Phase 3 clinical trial for ARX-04, the anticipated timing of top-line results from SAP-301, regulatory approval of ZalvisoTM, and the therapeutic and commercial potential of AcelRx Pharmaceuticals' product candidates, including Zalviso and ARX-04. These forward-looking statements are based on AcelRx Pharmaceuticals' current expectations and inherently involve significant risks and uncertainties. AcelRx Pharmaceuticals' actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, without limitation, risks related to: AcelRx Pharmaceuticals' ability to obtain sufficient financing to proceed with clinical development of ARX-04; the success, cost and timing of all product development activities and clinical trials, including the Phase 3 clinical trials for ARX-04; the market potential for its product candidates, including Zalviso and ARX-04; the planned meeting with the FDA to discuss their request for an additional clinical trial for Zalviso to address the risk of inadvertent dispensing and overall risk of dispensing failures; and other risks detailed in the "Risk Factors" and elsewhere in AcelRx Pharmaceuticals'U.S. Securities and Exchange Commission filings and reports, including its Annual Report on Form 10-K filed with the SEC on March 13, 2015. AcelRx Pharmaceuticals undertakes no duty or obligation to update any forward-looking statements contained in this release as a result of new information, future events or changes in its expectations.